METHODS: We report the case of an 83-year-old male with a history of myelodysplastic syndrome that progressed to acute myeloid leukemia, bipolar disorder, and benign prostatic hypertrophy. He presented with altered mental status and new onset lower extremity edema caused by acute bladder outflow obstruction. Computed tomography of the abdomen and pelvis showed the patient\'s distended bladder compressing bilateral external iliac veins.
CONCLUSIONS: Insertion of a Foley catheter resulted in several liters of urine output and marked improvement in his lower extremity edema and mental status a few hours later. Our extensive workup failed to reveal a cause of the patient\'s acute change in mental status, and we attributed it to a concept known as cystocerebral syndrome.